1. Field of the Invention
The present invention relates to an x-ray apparatus for dental use for generating panorama tomograms of the jaw of a patient.
2. Related Applications
The subject matter disclosed herein is related to the subject matter disclosed in the following applications: Ser. No. 942,812 filed Dec. 17, 1986 (Erich Heubeck, Werner Guenther, Manfred Muether and Leonard Werner); Ser. No. 942,800 filed Dec. 17, 1986 (Michael Doebert); and Ser. No. 942,747 filed Dec. 17, 1986 (Erich Heubeck, Manfred Muether and Dieter Molitor).
3. Description of the Prior Art
X-ray devices, and supporting structure therefore, are known in the art for generating a panorama tomogram of the jaw of a patient, wherein the x-ray source and a carrier for a film cassette are disposed at opposite sides of a rotary unit, with the holder for the film cassette being adjustably disposed such that x-rays from the radiation source are incident on the film substantially perpendicularly thereto. Such installations include an adjustment mechanism for adjusting the position of the film carrier in a curve corresponding to the mandibular arch so that the teeth can be successively imaged on the film in combination with the jaw.
In conventional x-ray diagnostics installations of this type as described, for example, in Brochure M-D 80/1361 for the ORTHOPANTOMOGRAPH 10, such exposures are possible only in a tomogram position permanently fixed for the apparatus. In order to make a larger diagnosis region available for standard or routine examinations, the exposure sequence is selected to obtain the greatest possible slice thickness. Because of such a large slice thickness, however, superimposed images can occur in which case important diagnostic details of the examination subject may be disposed behind one another. In some circumstances, this may lead to an incorrect diagnosis, or prevent a diagnosis being made at all.
From general x-ray technology, it is known to generate a plurality of parallel body slices simultaneously in x-ray images. This is known as the so-called "simultaneous slice method" and is described, for example, in German AS No. 12 44 555. Devices of this type cannot be used for panorama exposures, however, because a plurality of films having intensifier foils (film foil sets) must be arranged in a stack in a cassette, and the individual foil sets must be displaced parallel to each other during the exposure. This cannot be accomplished using rotational movement as is necessary to obtain a panorama tomogram.